In view of the increase in concern about environmental issues as well as economic efficiency, the demand for fuel efficient automobiles has been increasing in recent years. A need also exists for automotive tires excellent in fuel economy. Fuel economy is improved by reducing the amount of filler such as silica or carbon black to reduce rolling resistance. However, this technique tends to reduce wet grip performance and abrasion resistance. Automotive tires are also required to have handling stability, fatigue resistance, and tensile strength. Therefore, there is a need for techniques that achieve a balanced improvement in fuel economy, wet grip performance, handling stability, abrasion resistance, fatigue resistance, and tensile strength.
The following methods have been proposed to date: a method of using an appropriate combination of a specific rubber component, silica, and inorganic powder such as aluminum hydroxide to simultaneously obtain performance on wet roads, abrasion resistance, and low heat build-up properties (see, for example, Patent Literature 1); a method of using an appropriate combination of a specific rubber component, a specific inorganic compound powder, and a specific carbon black to improve grip force on wet roads and semi-wet roads and workability (see, for example, Patent Literature 2); and a method of using an appropriate combination of a specific rubber component, a specific inorganic compound powder, a specific silica, and a specific carbon black to improve grip force on wet roads and semi-wet roads without impairing abrasion resistance (see, for example, Patent Literature 3). Unfortunately, these methods still leave room for improvement to achieve a balanced improvement in fuel economy, wet grip performance, handling stability, abrasion resistance, fatigue resistance, and tensile strength.